Although many investigations have been conducted to characterize the pathogenesis of interstitial lung diseases (ILD's), few have examined the epidemiology of these disorders in a general population. To address current research needs related to the epidemiology of ILD's, I propose to establish a population- based registry of ILD's in Bernalillo County, New Mexico. Bernalillo county includes Albuquerque, the principal urban area of the state, and its population was approximately 420,000 in the 1980 census. There are 10 hospitals, with a total of 1,944 beds and 20 pulmonary physicians in the county. A major advantage of Bernalillo County as the site for the study is an already established disease surveillance system, the New Mexico Tumor Registry. Established case-finding procedures and staff are in place to identify new cases of cancer through histopathology records, and these resources will be adapted to identify new cases of ILD in Bernalillo County. Other sources of information for identifying new cases of ILD in the county include pulmonary physicians, primary care physicians, hospital discharage diagnoses, death certificates, and autopsies. Estimates from hospital discharge diagnoses in the county indicate that about 162 cases of ILD may be enrolled into the registry a year, for a total of about 700 cases during the four-and-one-half years of data collection. After a case of ILD has been identified from the various sources of information, data collection will include an interveiwer- administered symptoms questionnaire, abstracted medical record data, phlebotomy for measurement of serum percipitins, and evaluation of available chest x-rays and biopsy materials by a panel of B-readers and pathologists, respectively. Follow-up procedures will be used to determine the natural history of ILD's. The establishment of the registry represents the first step in a sequence of investigations designed to characterize the epidemiology of ILD's. The registry will initially serve a descriptive purpose; the incidence of ILD's will be measured in a defined population. Subsequently the registry will serve as a mechanism for ascertaining cases for a case-control study. Finally, the registry will provide population-based data for clinical purposes on presentation, physiology, and natural history of ILD's.